Get up close to a marvellous machine with the help of Archivist Matt Tantony.

Previously I wrote about my cataloguing work with our archival photographs. I’m really happy to tell you that we’ve just put an additional 1,149 newly catalogued and digitised photographs onto our online catalogue. To get technical, they’ve gone into several POST 118 sub-series, including the P Series, the Engineering Series and – new to the catalogue – the RES Series.

So what do these photos show? Most of the new ones come from a huge ‘Postal Mechanisation Library’, which reveals how the mail was made more efficient using machinery between the 1920s and 1960s, ranging from tiny experimental machines to massive mail sorting installations filling whole buildings.

I want to try something a little different with this post: rather than showing you a range of subjects, I’m going to show you how our photographic collections can illustrate the same subject… in lots of different contexts. All of the pictures below come from material I’ve catalogued and digitised in 2016.


A single position letter sorting machine (SPLSM) in use at the South Eastern District Office, 1959 (POST 118/16225)

This is a single position letter sorting machine – SPLSM for short. The operator typed in an address code as each letter passed through the lit-up window in front of him, and conveyors inside the machine whisked the letter away to one of the 144 stacking boxes along the side.

The above photo comes from the P Series of GPO publicity shots, and it shows an SPLSM in use at London’s South Eastern District Office (SEDO) in 1959. The image has been framed to show the then cutting-edge machine working harmoniously amidst the traditional wooden sorting frames and facing tables.

Norwich Letter Sorting Machine

Postal coding at Norwich, 1961 (POST 118/16229)

Here’s another P Series photo from 1961, which shows how an SPLSM dropped the sorted letters into the numbered stacking boxes. Can you read the address on the letter? It has an unusual feature for the time: a full postcode. This is in fact one of the ‘NOR’ postcodes used during the first postcode trials in Norwich, which is where this photo was taken. You can find out more about postcode history here.

Ideal Home Exhibition 1960

Letter sorting machine exhibit at the Ideal Home Exhibition, Olympia, 1960 (POST 118/15222)

The P Series of photos was maintained by the Post Office for use in public relations work, and this image is no exception. It shows an SPLSM on display at the 1960 Ideal Home Exhibition – in fact, it’s the very same machine that’s in the first photo in this blog post. It travelled all the way to Olympia from the SEDO in Borough to be part of the GPO’s exhibits, which also included postal history puppets and an interactive letter sorting game.

Letter sorting machine keyboard training

Letter sorting machine keyboard training, c.1957 (POST 118/16243)

Let’s leave the P Series behind and move on to the Engineering Series. These photographs extensively document the Post Office’s activities from the 1920s until the 1980s, particularly with regard to construction, transport, design and technology.

Above is one of several Engineering Series images I’ve catalogued showing SPLSM operators being trained in the 1950s and 1960s. Operators had to memorise the combinations of keystrokes used to sort the mail. Each operator had a numerical ‘ident’ that was printed onto letters as he sorted them, so that missorts and machine errors could be traced.

Southampton Sorting Office

Southampton Sorting Office, c.1960 (POST 118/16362)

In this Engineering Series photo you can see an SPLSM in use at Southampton Sorting Office in approximately 1960. Southampton Sorting Office hosted a number of experimental machines at this time.

While the SPLSM in the above photo is one of 20 machines produced by the Thrissell Engineering Company for the GPO, it’s nestled between two much-modified GPO prototype devices for sorting letters: a letter and packet segregator (on the left at the back) and an automatic letter facer (on the right). Indeed, the GPO’s own prototype SPLSM occupied this same spot in Southampton for some time until the Thrissell model replaced it in 1959.

First trial single position letter sorting machine

First trial single position letter sorting machine, c.1955 (POST 118/16222)

And here’s the prototype! Isn’t it magnificent? This photograph comes from the RES Series. As the name suggests, RES photographs were taken during GPO research and development activities.

The prototype single position letter sorting machine was worked on at the Dollis Hill Research Station and the Postal Engineering Development Unit at Mount Pleasant in 1954-5, then trialled and modified at Bath and Southampton.

In my cataloguing work I came across a number of RES photos of the prototype; these were later used in a specification document sent to companies tendering for the production models, explaining exactly how the SPLSM was intended to work.

First trial single position letter sorting machine

First trial single position letter sorting machine, c.1955 (POST 118/16265)

The RES images go into detail on the inner workings of the machine, making them a really helpful aid when consulting the trial reports and technical specifications held elsewhere in the Archive. In the picture above you can see how the SPLSM presented letters for coding one at a time in the clear window underneath the conveyors…

First trial single position letter sorting machine

First trial single position letter sorting machine, c.1955 (POST 118/16269)

…while this component, which looks like a cousin of Orac from Blake’s 7, was part of the machine’s control system.

Our collections at The Postal Museum are wonderfully broad, but I hope this post has given you an idea of just how deep you can go too, even within a single record series. Oh, by the way, we’ve also got one of the Norwich single position letter sorting machines in our museum collection.


– Matt Tantony, Archivist (Cataloguing)